Apron-type press



Dec. 27, 1960 H. w. GUETTLER APRON-TYPE PRESS Filed Dec. 51, 1958 4 Sheets-Sheet 1 HERBHT w auim ne AITORJUY Dec. 27, 1960 H. w. GUETTLER 2,966,112

APRON-TYPE PRESS Filed Dec. a1, 1958 4 Sheets-Sheet 2 INVENTOR.

HZ RBEIW W 61/ 7715/? ATTORNEY Dec. 27, 1960 H. w. GUETTLER 2,966,112

APRON-TYPE PRESS Filed Dec. 31, 1958 4 Sheets-Sheet 3 ATTORNEY United States Patent APRON-TYPE PRESS Herbert W. Guettler, 2901 Vallejo St., San Francisco, Calif.

Filed Dec. 31, 1958, Ser. No. 784,227

12 Claims. (Cl. 100-102) This invention relates to improvements in apron-type presses.

Various industrial processes produce waste materials containing considerable amounts of moisture. In many instances the waste material has utility if its water content is drastically reduced. For example, in paper mills large quantities of very wet bark are removed from logs, and withdrawal of most of its contained moisture renders the bark useful as fuel. Apron-type presses have been devised for squeezing out this water, and the instant invention presents improvements in such presses.

Apron-type presses are so named because a perforate apron extends around a substantial portion of the circumference of a large-diameter imperforate cylinder. The apron is urged in toward the cylinder under considerable pressure to squeeze out the water from wet waste material carried by the apron between itself and the cylinder. The water falls down through the apron, leaving the waste material much dryer.

Apron-type presses heretofore in use tended to trap small pieces of bark that fell down with the squeezed-out water, and these pieces of bark accumulated until they tended to plug the apron and sharply reduced the efficiency of its operation. When a chain-belt type of apron was used, the material accumulated in pockets below the top surface of the chain links and soon plugged the drainage spaces between the links. The present invention incorporates a novel chain-belt structure that eliminates such pockets. Moreover, the links are shaped to diverge from each other from the pressure surface downward, so that the spaces between links become wider and wider as one moves down. This structure encourages any particles of solid material that do fall down between links to continue on through and to fall into the water sewer.

In apron presses of the chain-belt type, the transverse openings between successive links are opened wider when the apron runs over its drive sprockets, which are located near the end of the apron, where the compressed and de-moisturized bark is dumped off the apron. This opening up of the belt inevitably results in some bark getting in between links. This bark, and any other that may get between links, should be removed. In the past, belts tended to get so clogged that the press had to be stopped from time to time and thoroughly scrubbed to get rid of the accumulated solids. To avoid stoppage so often, jets of water were sprayed on the inside of the return reach of the apron in an attempt to wash the entrained bark particles into the sewer. However, along this return reach the inside edges of the links tend to converge and limit the eifectiveness of this method. The present invention solves this problem and gets the belt clean by impinging water jets against the outside of the apron, preferably shortly before the point where the apron first converges toward the cylinder and is charged with Wet bark. By washing the bark particles from the outside in, they are more easily dislodged from the belt. The wash water and bark are caught and conducted Patented Dec. 27, 1960 away, so that it does not run back onto the apron. Moreover, the nozzles that do the washing are specially located to give improved results.

This invention also incorporates a novel feature of having every second chain strand in the apron consist of drive links and the alternate strands be non-driven. This gives the large number of drive strands needed to transmit the hugh amount of power required, while still spacing the sprocket teeth apart, enabling eflicient employment of the hubs by which the driving sprockets are keyed to their shaft.

Thus improvement of the link structure and keeping the links clean is one important area of this invention. As will be seen, there are still further improvements .in this area, including important changes along the side edges of the apron and of its relation there with the cylinder, to hold the bark against indiscriminately spilling off there. These other features receive attention in the detailed description that follows later.

Another important area of this invention relates to improvements in the means by which pressure is applied to the apron to squeeze the bark tightly between it and the cylinder. Here, also, many diflicult problems have been solved. For one thing, the pressure is applied at somewhat different locations than in the prior art, giving better filling between the apron and the cylinder and more efficient squeezing action. For another, the pressure is applied in a way that prevents damage to the pressure-applying means, which had occurred in the past due to the inevitable unevenness of the bark mat and the resultant tipping action from side to side at each pressure roll. Instead of transmitting that action to the pistons, with resultant wear on their packing and consequent leakage from their hydraulic cylinders, the piston rods are made to float relatively to their bearings, an action which also reduces wear. Among still other novel features are the variation in cylinder diameter and piston stroke employed at the different pressure-applying stations to effect maximum efliciency and simultaneous economies of operation.

Another novel area of the invention relates to the trunnion support of the cylinder, whereby the tremendous loads-up to tons in machines now operating-can best be resolved without undue wear.

All these and still other features, objects and advantages of the invention will appear from the following description of a preferred form of the invention that is exemplary of its principles.

In the drawings:

Fig. 1 is a view in side elevation of an apron press embodying the principles of the invention.

Fig. 2 is a view partly in end elevation and partly in section, taken along the line 22 and 2 a in Fig. 1.

Fig. 3 is a fragmentary view on an enlarged scale in side elevation of a portion of the apron in the arcuate disposition it assumes as it passes around the cylinder, with portions broken away to show parts behind.

Fig. 4 is a fragmentary view of the apron, taken along the line 4-4 in Fig. 3.

Fig. 5 is a fragmentary enlarged view in end elevation and partly in section of a portion of the apron washing section of the device, taken generally along the line 55 in Fig. 6.

Fig. 6 is a fragmentary enlarged view in side elevation and in section, taken along the line 6-6 in Fig. 2. Fig. 7 is a fragmentary enlarged view in end elevation and in section of a portion of the side edge of the apron and cylinder, taken along the line 7-7 in Fig. 1.

The apron press of this invention includes a suitably constructed and braced frame 10 with two side-frame members 11. A cylinder 12 of very large diameter (e.g., about five feet) has its trunnions 13 rotatably mounted in bearings 14 that are secured to each side frame 11. A heavy chain-belt apron 15 encircles the cylinder 12 for about 80. The apron 15 is driven from a series of sprockets 16 mounted on a shaft 17, which in turn is 'rotatably supported by frame-supported bearings 18. The

shaft 17 may be driven by any suitable means. For

example, the drive may comprise an electric motor 20,

a reducing gear 21, a pinion 22, and a' gear 23' keyed to the shaft 17. The cylinder 12 may be separately driven, if desired, but ordinarily is driven only indirectly via the apron 15. 7

Threepairs of hydraulic cylinders 25, 26, and 27 are rigidly mounted to frame 10, one of each pair to each side-frame member 11. The axis of the'third cylinder 27 preferably is vertical and in line with the axis of the tive piston rods 23, 23, and 31? against pairs of bearing blocks 31, 32, and 33. Each block 31, 32, 33 is slidable along a respective guideway 34, 35, 36, and each pair of bearing blocks supports a pressure roll 37, 38, 39 for free rotation therein.

Wet bark or other waste material 40 is fed into a hopper 41 from a conveyor 42 (or by other suitable means) and is forced between the apron 15 and the cylinder 12 to make a mat 43. Thus the apron 15 with its bark mat 43 supported thereon, is forced by the pressure rolls 37, 38, and 39 toward the cylinder 12 under considerable pressure, thereby squeezing out most of the water, which falls down through the apron 15 into a suitable sewer 44. The pressed bark mat 43, now of substantially reduced thickness, rides the apron 15 as it leaves the cylinder 12 and goes over the sprockets 16. There a bark stream, 45 drops oif onto a conveyor 46, which may carry it directly to a power plant for fuel, or may carry it elsewhere for other uses.

Thus, the wet bark 40 enters the press ata throat area 47 instead of being throttled at its entry by mounting the cylinders 25 horizontally along the radius of the cylinder 12. The mounting of the cylinders 25, piston rods 28, and first pressure roll 37 is. thus an important feature of the invention.

Another feature of the invention is that the pressure applied at the three pressure rolls 37, 38, 39 is successively increased. At the first pressure roll 37, the bark mat 43 is thick and wet and its variation in thickness is great. At the second, pressure roll 33, the mat 43 is already much thinner and dn'er and can be given more pressure, while still more pressure can be applied at the third pressure roll 39. For example, the respective sets of hydraulic cylinders may have respective inside diameters of six inches, seven inches, and eight inches, to give the desired increases in pressure at each step. At the same time, the decrease in thickness of the mat 43 is accompanied by reduction in the variation in thickness. Consequently, the strokes of the piston rods 28, 29, and 30 can be successively reduced, for example from eight inches to seven inches to six inches. This successive increase in pressure with concomitant decrease in stroke saves oil in significant amounts and also saves on materials, while giving improved operation.

Due to the inevitable unevenness in the bark mat 43, the pressure rolls 37, 38, 39 are tipped back and forth on their bearing blocks 31, 32, 3-3. In the past, this force acted on the piston rods and resulted in wear on them and on the bearing blocks. More important, the rocking action tended to bend the piston rods against the packing between the piston and the cylinder, thereby ultimately causing leakage in the cylinders with resultant loss of pressure, so that the press became less effective as time went on. In the present invention the rocking movement is rendered harmless by providing a separate nose piece 48 that is screwed into the end of each piston rod 23, 23, 3G and a pressure block '49, that is bolted to each bearing block 31, 32, 33. Both these parts 48, 49 are preferably made from hardened steel and are remotable from their respective supporting members for replacement. Their flat contact surfaces produce a fioating action that allows free movement at their meeting surfaces; so the pistons are unaffected by the rocking or tipping of the pressure rolls 37, 38, and 39.

The apron 15 (see especially Figs. 3 and '4) is made of three types of links. Every other strand is made up of drive links 50 that engage the sprockets 16. Between every pair of strands of drive links 50 is a strand of intermediate non-driving links 51. Along each of the two outside edges is a strand of marginal or end links 52. This spacing of the drive links 50 gives the maximum amount of drive surface for the sprockets 16, while still giving room for hubs 16:: by which the sprockets 16 are secured to the shaft 17. Each link 50, 51 has a pair of hubs on each side, and each end link 52 has a pair of hubs 55 on one side. Each hub 55 extends out laterally from the link 53, 51, or 52 beyond the upper surface 56 (which is identical in all links 50, 51, 52) and engages a hub 55 of the adjoining link to space the links apart laterally to define openings 57 through the apron 15, through which water may escape. Each hub 55 defines a cylindrical opening 58 (see Figs. 6 and 7) through which extends a transverse locking pin 59, which ties the strands together in staggered relation. The end links 52 have recessed lower portions 60 so that retaining nuts 61 can be bolted to outer threaded ends 62 of the pins 59 and so that the nuts 61 are flush with the end 63 of the upper surface 56 of the links 52 (Fig. 7). This means that the apron 15 has an effective width for its full actual width.

Fig. 7 shows a portion along one side edge of the cylinder 12 and apron 15 with the bark mat 43 between these and adjacent the side frame 11. In order to contain the bark between the cylinder 12 and the apron 15, an arcuate side plate 64 is bolted to the side frame 11 by a flange 69 closely adjacent the edges of the cylinder 12 and apron 15. Note that it is close to the edges 63. The plate thus keeps the bark from falling out the sides. The overhung ledge provided by the outer links 52 covers the nuts 61 and extends lengthwise the full length of the links 52 so that the bark will not fall out between the nuts 61. V

The links 50, 51, and 52 are proportional so that there are transverse openings 65 between the links of the same strand (Figs. 3, 4 and 6), forming additional places for the water to escape when it is squeezed out. In the links 51 and 52, the forward and rear faces 66 are planar but slope so that they diverge downwardly, even when the chain strands are horizontal and even more when the apron 15 is around the cylinder 12, atwhich time its curved upper surfaces 56.1ie along a common cylinder. This divergence aids in preventing any particles of bark that get through the openings 65 from sticking to the links 51 and 52, and the planar surfaces help too. The links 50 cannot have planar end surfaces, but the upper portions 67 of these end spaces diverge, as do the sprocket-engaging lower portions 68, which are rather S-shaped in cross sectiontFig. 3), the lower portions of which blend into and become part of the hubs 55.

On all the links 50, 51, 52, the side faces 70 diverge downwardly and are planar, except for the hubs 55 (see Fig. 5). The diverging faces of the links aid greatly in keeping bark particles from sticking to the links and plugging the vital drain openings 57. There are no pockets to catch the bark particles and hold them. Moreover, the planar surfaces help because anyparticles that do lodge there are all the more readily dislodged.

However, some particles do inevitably lodge on the links 50, 51, 52, and the present invention provides for this also. Some particles may lodge during the squeezing pass, some may get in when the apron 15 passes over its drive sprockets 16, with resultant opening of the spaces 65, and others may fall on the aprons under side While it moves along its return reach 71. These particles would all be difficult to clean out along the return reach 71 since the transverse openings 65 converge downward there. In order to clean out these particles, I provide an idler tail drum 72 at the top of the loop described by the apron 15, just before it begins its downward run to the pressure roll 37 and its run around the cylinder 12.

The drum 72 (see Figs. 1, 5, and 6) is made of two end rings 73 and a series of bars 74 secured to the end rings and extending between them axially of the drum. The bars 74 may be round pipe or rods, but preferably are generally rectangular or trapezoidal with downwardly diverging sides 75. The bars 74 are circumferentially spaced apart and this spacing and the diverging sides 75 provide axial drain openings 76 that will let water through. The idler dnlm 72, driven by the apron 15, rotates on trunnions 76 that engage the end rings 73. A water trough 77 extends axially through the idler drum 72 and out beyond one of its open ends into a drain pipe 78 that leads to the sewer 44.

Above the idler drum 72 the frame supports a series of spray nozzles 80 and 81 (Figs. 1, 2, 5, and 6). The nozzles 80 are aligned with and spray through the longitudinal openings 57 between strands, while the nozzles 81 are aligned with the center of each strand to clean out the openings 65. These nozzles 80 and 81 serve to wash the bark particles away from the apron and through the idler drum 72 into the trough 77 and drain pipe 78. If desired, the drain pipe 78 may lead to a screen instead of going directly to the sewer 44, for recovery of particles. The nozzles 80 and 81 are on a horizontal pipe 82, supplied through water pipe 83 with water from any suitable source.

Suitable frame brackets 84 and 85 support the shower pipe 82 and the trunnions 76.

When the cylinder 12 rotates with its trunnions 13 in the bearings 14, very great pressure is exerted on the cylinder, trunnion, and bearing by the hydraulic pressure rolls 37, 38, and 39. In large presses this pressure is over 100 tons for each side. The present invention incorporates a novel design by which the trunnions 13 are connected to the cylinder 12 in a way that reduces to a minimum the unit stresses in all these parts. The hearing 14 is bolted to a corner bracket 90 which is welded to the steel frame 10. The steel frame 10 has wide flanged beams that give sufiicient strength, and the bracket 90 is made of the same type of beams in line with the frame beams. The center line of the bearing 14 is located along the center line or structure 91 of the beams. The trunnions 13 have flanges 92 that are bolted to flanges 93 on the cylinder 12 (see Figs. 2 and 7). The connection between the flanges 92 and 93 is located as close to the inner surface of the cylinder 12 as is practical by using very shallow flanges 93 so that the bolts 94 have the greatest feasible amount of leverage, enabling them to withstand bending moments. The trunnions 13 and their flanges 92 thus form the ends of the cylinder 12. Moreover, the weakest section of the trunnion-its line of connection 95 with the flanges 92is located as close to the center line of the bearing 14 as possible, and, as shown, is actually within the area defined by the edges of the frame. This action keeps the bending moment as low as possible and therefore enables the thickness of the trunnion 13 to be kept to a minimum.

To those skilled in the art to which this invention relates, many changes in construction and widely difiering embodiments and applications of the invention will suggest themselves without departing from the spirit and scope of the invention. The disclosures and the description herein are purely illustrative and are not intended to.

be in any sense limiting.

I claim:

1. In an apron-type press having a cylinder mounted for rotation and an endless apron of pivotally connected links disposed in parallel staggered rows with one run of the apron extending about a portion of the circumference of the cylinder, the improvement comprising having each link provided with sloping end walls and being spaced longitudinally from links in the same strand and straight sloping side walls and hub means spacing them laterally from links in other strands, so that there are openings between the end walls of successive links and between the side walls of adjacent links, said end and side walls sloping so that all said openings widen smoothly from the top of the links to their bottom when they are in the run along along the cylinder.

2. In an apron-type press having a rotatable cylinder and an endless apron of pivotally connected links disposed in parallel staggered rows, said links being spaced laterally and longitudinally from each other to provide respective longitudinal and lateral openings through which water is squeezed from wet solid matter in said press as said apron follows an arc of the circumference of said cylinder for a portion of its path, the combination therewith of means for washing out solid matter that sticks to said links in said openings, said means comprising a rotatable perforate drum over a portion of which said apron passes before reaching said cylinder, a series of nozzles above said drum for playing water jets on said apron as it passes over said drum, and means for collecting the water that passes through said apron along with the washed-out solid material and for conducting it away.

3. The device of claim 2 wherein said drum is made up of two end rings and a series of longitudinal bars connecting said rings, said bars being spaced apart from each other circumferentially to give axially extending openings for the water to pass through.

4. The device of claim 3 wherein the drum is rotatably mounted at each end on a pair of trunnions that engage the inner surface of said rings.

5. The device of claim 2 wherein the last-mentioned means inside said drum comprises a longitudinally extending stationary trough inside said drum and a conduit leading out from one end of said trough and passing through and beyond one end of said drum.

6. The device of claim 2 wherein one set of spray nozzles is positioned in alignment with each longitudinal opening between links for washing material out therefrom.

7. The device of claim 6 wherein another set of nozzles is positioned over the middle of each row of links for sending Water into the lateral openings between links.

8. In a press for dehydrating material an imperforate rotary cylinder mounted for rotation and an endless perforate apron of pivotally connected rigid link construction which passes around a portion of the circumference of the cylinder for squeezing material therebetween and pressure means for urging said apron toward said cylinder, the improvement wherein said pressure means comprises a series of pairs of hydraulic cylinders each having a piston rod projecting therefrom toward said apron, a bearing block mounted for sliding movement along a radial line of said cylinder and urged outwardly by each said piston rod, and a pressure roll journaled in each pair of bearing blocks, there being initial cylinders which force the apron in toward said rotary cylinder at the beginning of the run around said rotary cylinder, the initial cylinders being of smaller diameter than the subsequent cylinders, the subsequent cylinders getting successively larger, to apply gradually increasing pressures toward the end of the run, the stroke of the initial cylinders being the longest and the stroke of each subsequent cylinder successively diminishing in length.

9. In an apron-type press having a cylinder mounted 7 s V 7 V a for rotation and an endless apronof pivotally connected links disposed in parallel staggered rows of strands with one run of the apron extending about a portion ofthe circumference of the cylinder, the improvement comprising having each link provided with sloping end walls and being spaced longitudinally from links in the same strand andtsloping side Walls, and being spaced laterally from links in other strands, so that there are openings between the end walls of successive links and between the side walls of adjacent links, said end and side walls sloping so that said openings widen from the top of the links to their bottom when they are in the run along the cylinder, every other strand comprising drive links with their end walls shaped in a generally S-curve formation, a drive shaft, hub means, a plurality of drive sprockets for driving said drive links, said sprockets being mounted on saiddrive shaft by and spaced from each other by said hub means, said hub means projecting beyond the sprockets on each side by substantially one-half the width of said links and being aligned with intermediate nondriving links.

10. In a press for dehydrating material an imperforate cylinder mounted for rotation and having an inner surface and an outer surface and an endless perforate apron of pivotally connected rigid-link construction which passes around a portion of the circumference of the outer surface of said cylinder for squeezing material therebetween,

and pressure means for urging said apron toward said cylinder, the improvement wherein said cylinder has a pair of annular flanges extending radially inwardly a short distance from said inner surface, the flanges being spaced inwardly a short distance from the ends of the cylinder, and discs having integral trunnions thereon closing said ends and secured to said flanges, said discs having peripheries spaced close to said inner surface.

11. The device of claim 10 having a supporting frame spaced closely adjacent to the ends of said cylinder and bearings centered on said frame and supporting said trunnions very closely adjacent the edge of said cylinder.

12. The device of claim 11 wherein said discs are slightly conical and said trunnions are connected to them beyond said cylinder ends and within the boundaries of said frame.

References Cited in the file of this patent UNITED STATES PATENTS 

